1. Field of the Invention
The invention is directed to a format recognition device for a film cassette, particularly an x-ray film cassette, whereby the format of the film cassette is electro-optically detected by means of at least one radiation receiver.
2. Description of the Prior Art
X-ray film cassettes are employed in x-ray diagnostics installations for producing x-ray exposures of a subject. It is known to detect the format and the size of the film cassette by electromechanical means. Electromechanical means, however, are complicated to manufacture and thus are expensive; they are also subject to wear.
German PS 32 32 148 discloses that the format and the size of the film cassette be detected by means of a light barrier arrangement. The light barriers are rotatably mounted at a location in the cassette holder at which measurement of a set length or width is made as film cassette is inserted in the holder. A gap is presenting the light barrier at a position allocated to the format based on the length and on the width of the film cassette, so that the format can be recognized on the basis of the signal caused by the light passing through the gap of the light barrier.
European Application 0 202 832 discloses a method and an apparatus for sorting articles, particularly tableware, whereby an occlusion of photoelectric cells, and thus recognition of an article, ensues on the basis of the length and width, i.e. on the contour of the tableware.
German OS 28 37 112 discloses an apparatus for the automatic identification and registration of bottles having different sizes and/or shapes. The identification of the bottles ensues on the basis of individual occlusion patterns that are stored in a memory.